Florida Sen. Marco Rubio got booed off a stage in Orlando on Sunday by a crowd that was overwhelmingly Latino.

It happened at Calle Orange, a street festival in downtown Orlando geared toward the city's large Puerto Rican community. The icy reception was an indication of the challenges that Rubio, a Republican of Cuban heritage, has faced in locking down support from Latinos in Florida as the state's Latino electorate has begun to shift to the left.

Some Latinos, including several people in the crowd, have expressed anger over his endorsement of Donald Trump, who kicked off his presidential campaign last year by disparaging Mexican immigrants.

At first, there was no visible hostility toward Rubio when he arrived at the festival on Sunday. He was greeted by a group of volunteers wearing Rubio campaign T-shirts and playing Plena, a rhythmic style of music native to Ponce, Puerto Rico. The musicians accompanied Rubio as he and his aides walked toward the stage. He stopped for selfies along the way.

But when he took the stage, there was a spattering of boos from the crowd. When the emcee introduced the senator, they grew louder.

"I'm going to introduce a man who represents Latinos, no matter where you're from," the emcee boomed in Spanish. The boos grew louder still. "Ladies and gentlemen, the senator for the state of Florida, a Latino like you and me ... his name is Marco Rubio! Applaud!"

Instead, the boos rained down on the senator, drowning out what appeared to be a handful of supporters in the crowd.

"Thank you for having me today," Rubio said, also in Spanish. "I want you to enjoy this day. We're not going to talk about politics today. Thank God for this beautiful day, and for our freedom, our democracy, our vote and our country. God bless you all, thank you very much."

Then he left the stage, to more boos.

His appearance at Calle Orange seemed to be an embarrassing miscalculation for Rubio, who is locked in a tight race for re-election against his Democratic challenger, Rep. Patrick Murphy. The most recent CBS News/YouGov poll of the race showed them tied among Florida Hispanics at 40 percent.

As Rubio left the stage, I asked him twice why he thought the crowd had reacted negatively, but he ignored my questions.

Rubio's campaign defended his appearance at the festival in an email, calling it "very positive" overall:

"Marco kept his remarks short at the request of the hosts since it was not intended to be a political gathering. Marco has worked hard on behalf of the Puerto Rican community — from leading efforts to help Puerto Rico out of its financial crisis, to awarding the Borinqueneers with the Congressional Gold Medal, and making student loans more affordable. If re-elected, he will continue to fight for the best interest of Florida's Hispanic community."

Those in the crowd, however, were eager to give their take.

"Latinos might have differences amongst each other, but we're also united as one," said Angel Marin, a retired Army sergeant of Puerto Rican descent who said he has voted for both Democrats and Republicans. He said he resented Rubio for his endorsement of Trump.

"And when we have someone like Trump, who hits our Mexican brothers, our Latino brothers, then you jump on that bandwagon after all that stuff he says not only about you personally ... as a Latino, you're a freaking sellout. I would not vote for him if they paid me."

"He's from the party of Trump," Gretchen Valentin, who lives in Orlando, said in Spanish. She characterized her feelings toward Rubio as more distaste than dislike. Valentin moved to Florida from Puerto Rico 15 years ago, but said this election would be her first time voting. "I've never belonged to any political party, but this year, I'm inclined toward the Democrats. The little I've seen of Trump and the Republicans and how hard they've made it for immigrants has left me unconvinced with them."

But it also points to the difficulty the GOP has had in hanging on to Latino support statewide. Ten years ago, there were more Latinos registered as Republicans in Florida than were registered as Democrats. Today, that has flipped. And that's not just because of the thousands of Puerto Ricans who have left the island and settled in Central Florida in recent years. Young Cuban-Americans are also trending Democratic.

Florida also has large populations of Venezuelans and Colombians.

Rubio's Spanish-language outreach in the current campaign has showcased his understanding of differences between all of these groups. In one radio ad now airing on Spanish-language stations, Rubio voices support for people he says have been oppressed in Cuba, for sanctions against Venezuela's socialist government, and for a resolution to the decades-old war in Colombia.

At the festival in Orlando, the musicians singing pro-Rubio slogans to the rhythm of Plena made his campaign sound like Puerto Rico.

The only problem for him was that most of the Puerto Ricans in the crowd didn't buy it.